Transmission system



June'lO, 1930 F. J. SINGER TRANSMISSION SYSTEM Filed May 4, 1928 INVENTOR BY (Si/we! ATTORNEY Patented June 10, 1930 star Wire? EM oFFlcE.

FRED J'. SING-ER, F BOCKVILLE CENTER, NEW YORK, ASSIGNOR TO AMERICAN TELE PHONE AND TELEGRAPH COMPANY, A CORPORATION OF YORK 'rnAnsivrIssIcN svs'rnm i r Application filed MayA This inventionrelates to telegraph transmission, receiving and signaling systems. More particularly, this invention relates to arrangements for converting pulses or pulsations of alternating current into corresponding direct current pulses or pulsations. Still more particularly, this invention relates to arrangements interconnecting an alternating current relay, thewinding of which is energized with pulses or pulsations of alternating current, and a directcurrent relay, the armature of-which is to control the operation oi a telegraph line or other signaling circuit so that pulses or pulsations of direct current maybe transmitted over the telegraph line orother signaling circuit in accordance with the pulses or pulsations of alternating current energizing the winding of the alternating. currentrelay. Heretofo're, pulses orpulsations of alternating current, which may be characteristic of telegraphy, or of other signals, were transmitted over an elcctricalcircuit, one of these pulses or pulsations representing, for example, a marking signal, and theabsence of that pulse or pulsation, a spacing signal. At the distant or receivingterminal of the system, an amplifier, frequently of the vacuum tube type,was employed for the purposeof amplifying thesealternating current pulsations. Coupled to the amplifier there was a detector, frequently, also of the vacuum tube type, this detector being employed to rectify. the receivedand amplified pulsations and to transform these pulsations into correg spending direct current pulsations. It was also thepractice to so relate a direct current relay to the output of the detector or rectifier that the armature of this relay might move, back and forth between its contacts and thereby control and operate another electrical. circuit, which may, for example,

be a telegraph loop. Such an arrangement is well known to bequite expensive in its first cost as well as in its operating charges. It is proposed to substitute for the amplifier, detector 3 or rectifier, em, a relay system which may include analternating current relay upon the Winding of which maybe impressed high frequency signals which may 1928. Serial No. 275,165.

be merely alternating current pulsations, illldjlflllQCl? current relay properly related and connected to the alternatnig current relay, so that the armature of the direct cur rent relay may control the operation of another .circuit which maybe the above mentioned telegraph loop.

Thus, it is oneof the objects of this invention to provide a receiving circuit for recciving and/or detecting modulated high um tube circuits.

Another of the objects of this invention is to properly interconnect a tuned, sensitive alternating current relay which may be energized by alternating current pulses, and a direct current relay controlling a receiving c0 frequency signals substantially without distortion and not necessarily including vacucircuit, so that the direct current relay may control thetransmission of pulses of direct currentto the receiving circuit corresponding ,to the impressed alternating current pulses. i

A fu rtherobj ect of this invention is to provide a receiving circuit which may include-a direct current relay, the windings of which may become energized low voltage currents, which may be signaling currents, and the armature of which may control the transmission of highervoltage currents to the receiving circuit, or conversely, a s m lar arrangement may be employed in which the voltages of the respective currents are inverted in their relative magnitudes;

And it is a still further object of this invention to combine an alternating current relay, the armature of which may vibrate at a definite periodicity when alternating current of corresponding frequency is impressed uponthc winding of that relay, andthe are.

in r

duce any signals which may be modulated upon carrier current sent from the distant station.

, jects and features, may be better understood nating current pulsations.

I terms.

from the detailed description hereinafter following, when read in connection with the accompanying drawing, in which Figure 1 represents one embodiment of the invention, including an alternating current relay upon the winding of which pulsations of alternating current may be impressed, and a direct current relay the armature of'wh-i'ch vibrates in accordance with the signals represented by thealternating current pulsations, and Fig. 2 representsa modification of the arrangement shown in Fig. 1.

Referring to the drawing, L designates an electrical circuit over which may flow alter- These alternating current pulsations may,'for example, be produced by an alternating current generator, the output of which is interrupted at more or less regular intervals so that these pulsations may be characteristic of signals such as are employed in telegraph signaling sys- These pulsations may become impressedi upon a filter F, which may be of any well-known type, preferably a band pass filter of the type disclosed in Campbell Patent 1,227,113, datedMay 7, 1917. Thus, this band pass filter may freely transmit alternating current, or currents, of frequencies which are quite close to the frequency of the generator employed at the transmitting terminal of the system. It will be understood, however, that in practice the employment of the filter may not be deemed necessary, and this is especially so if the alternating current relay receiving the alternating current pulsations is'tuned to the particular frequency of the generator.

The filter F is connected to a potentiometer P so that the voltage of the current trans mitted thereby may be controlled as found necessary. These pulsations are then impressedupon the winding of an alternating current relay R the armature of which may vibrate substantially in accordance with the frequency of the current of each pulsation, this current beiing frequentlydesignated carrier current. Relay R is preferably a highly tuned polar relay. Its armature may preferably be biased against its contact. Thus, this arn'iature may be made to normallycloseits contact by attachinga spring, for example, thereto, or it may be biased magnetically or el'ectromagnetically, or gravitationally due to. its weight, or in. any other well-known manner. l

The reference character R designates the direct current relay having two. operating windings and W and. a third winding W which may form part of a so-called vibrating circuit. It will be apparent that the windings of the direct current relay may be coupled to one another so that the magnetic field established by the current flowing through these windings may tend to move the armature of thedirect current relay back and forth between its contacts S and M. A battery B may be employed to energize the operating windings of the direct current relay. In series with battery B there is the resistance element of a potentiometer P so arranged that the entire battery potential is impressed upon the terminals of the poten tiometer. The slidable contact of potentiometer P may be manipulated so. as to make any portion of the potential of battery 13 available. Accordingly, the magnitude of the potential to be impressed upon the operating windings of the direct current relay and upon thearmature and contact of the alternating current relay. may be decreased to any desired value. A choke coil K is interposed between the slidable contact of the potentiometer P and the contact of the armature of the alternating current relay T The operating winding W of the relay R is connected in series with the armature of relay R and its contact as well as with a resistance Z The other of the operating windings W of relay R is connected in series with another resistancev Z Thus, the current derived from. battery B 'also flows through the choke coil K and through parallel paths, one of which includeswinding V resistance Z and the armature of relay R and its contact, and the other of which includes the winding WV andresistance Z It will thus be apparent that as the armatureof relay R vibrates in accordance with the frequency of an impressed carrier current, pulses will be received by the operating windings W1 and WV of the direct current relay R these pulses corresponding to the number of times the armature of relay B closes its contact and not necessarily corresponding to the frequency of vibration of the armature. It will also be apparent that windings W and VV are preferably oppositely poled so that the magnetic field established by one of these windings may cause the armature of relay R to move towards one of its contacts, while the magnetic field established by the other of thesewindings may cause that armature tomove to the other of its contacts. Moreover, the resistances Z and Z may be so proportioned that the magnetic field establishedby one of the windings is considerably greater than the magnetic field established by the other of the windings, so that when current flows through both windings, the, armature of relay R will be held in position against a particularone of its contacts. For example, resistances Z and Z may be so proportioned that the current nected through aresistanceZgto a battery B", and B and that the potential of battery. B may, if desired, be substantially lower, than the potential, or potentials, of batteries flowing through the winding W and, consequently, the magnetic field established there.- by, may be twice as great as the current flow: ing through the winding W and the mag netic field established thereby, and, since the effect of winding is, therefore, greater than that of W the armature will be caused to close contact S. Obviously, when the armature of relay R does not close its contact, no current will flow through winding W and therefore winding W will eiiectively cause the armature of relay R to close contact M. a

a A circuit,which may be a localcircuit,a telegraph loop, or any other circuit, is designated by the reference character L This circuit is shown under, the control of the armature of relay R Contact M maybe con nected in serieswith abattery Bz through a resistance Z While contact S may. be con- B which may beer the same potential as battery B butof oppositepolarity. Thus, as the armature of relayR moves back and forth between its contacts, current mayflow over line L from either of the batteries B7 or B Y l/Vinding VVa of relay R may be connected in aso called vibrating circuit, the operation of which willbe described later.. This circuit isshown in Fig.1 to include windings W} and W which may be inductively coupled toeachother, and which may form the primary and secondary windings of a trans former, a condenser G and winding W of relayR- Line L is connected to ground through a resistance Z condenser C and winding W It will alsobe apparent that the potential of battery 13;, may be substantially different from the potential, or;potentials, of batteries Bf and B7 Accordingly, current of substantially low Voltage may flow through the operating windings and W of relay R and through the armature and contact of re-,

lay R while current of substantially higher voltage may be supplied to the line L It will be understood, however, that the rela-. tive magnitudes of these voltages may be reversed so that the voltage of the current "flowing through the operating windings of relay R may be higher than the voltage of the current with which line L is supplied.

When a distant station may be sending a specific signal, such, for example, as atele graph spacing signal, noalternating current will flow through the winding of the relay R sothat its armature may close the associated contact Currentwill then flow throughthe windings W and 3W jot relay R this cur rent being derived from battery B themaga nitude ,ofthe efiective voltage otthis currentl ing contact- S when that tentiometer P As has already been stated, a the current through winding W which is poled in opposition to winding VV will cause the armature of relay R to close its spacing contact S. It will be clear that the resistances Z andZ as well as the resistance of the potentiometer P may be so proportioned that the voltage across thearn'iature of relay 1%, and its contact is less than a predetermined value. Accordingly, sparking at its contact may be practically eliminated. And when the armature of relay R remains fixed against its contact, the armature of relay R willbe similarly fixed against contact When the distant station may be transmitting a telegraph marking signal, alternating current will flow over line L through filter F, potentiometer P and the winding of relay R causing its armature to vibrate therewith. As the armature of relay B vibrates, the circuitthrough winding V1 may become opened and closed periodically, while the circuit through winding remains closed. Relay R may be so designed that when current of a particular frequency is impressed uponits winding, itsxarmature may close its associated contact substantially fewer times than thefrequency of vibration of the armature. Thus, during the transmission of i a marking signal there may be several cycles ofcarrier current transmitted and thearma; ture of the relayR will vibrate a corresponding number of times. The contact of relay R however, may be closed only duringa small percentage of the time, as stated hereinabove, land, therefore, the average current through winding W may be quite small. Incidentally, the average current through winding I V becomes increased because the average potential across its terminals is in creased, for it is afact that more current may flow through winding W when the contact of the armature of relay R is open than when thisarmature contact is closed.

The action of windings W and W and the action of the so-called vibrating circuit to be subsequently described, cause the armas tureof relayR to move back and forth between its contacts M and S as suitable alternating current is or is not impressed upon the windingof relay R If a telegraph key were employed at theidistantstation to control the transmission of alternating current therefrom, the armature of relay lti would key were closed, andit would closethe spacdistant key were opened. l i l i It will be clear that when the armature of relay R closes the marking contact M, this contact, remains closed throughout the time that suitable current is impressed upon the winding of relay R At all other times, this close the marking contact M when the distant armature may close its spacing contact S. The choke coil K is so related to the circuits interconnecting the relays R and R as to damp out any sudden impulse which may be caused by the brief closure of the contact of relay R during its vibrations. -Accordingly, the current through winding V7 is effectively prevented from momentarily becoming large and Z One diagonal of the bridge includes battery B a resistance Z and ground. The other diagonal of the bridge includes the armature of relay R its contact and choke coil K. It will be apparent that resistances Z Z Z and Z may be so proportioned that when the armature of relay R definitely closes its contact, the windings W and W will establish proper magnetic fields to move the armature of relay E to its spacing contact S. -And when the armature of relay R vibrates, due, for example, to the presence of a suitable pulsation in line L the armature of relay R may becaused to close its marking contact M. Thus, the magnetic field established by one of these windings may be stronger than that established by the other when a suitable pulsation is impressed, and, conversely, the magnetic field of the latter -winding may be greater than that of the former when no such pulsation is impressed. It will be understood that while this Wheatstone bridge arrangement may be balanced so that no current may flow through the diagonal including the armature of relay R when the armature of that relay is fixed against its contact, this bridge is preferably unbalanced so that'an appreciable current maynormally flow through the diagonal including the armature'of relay R Another feature of this l/Vheatstone bridge arrangement is that it is designed to limit to a definite value the magnitude of the voltage across the armature and contact of relay R Winding W of relay R is connected in what is known as a vibrating circuit. The, purpose of this circuit is to render the relay more sensitive to currents flowing through windings WV and and to prevent chattering or rebound of the armature when it strikes contacts M or S. In the form of vibrating circuit shown in Fig. 2, winding TV, is connected in a series circuit including a resistance Z condenser G and ground. The midpoint of winding W is connected to the fixed terminal of the armature of this relay.

. When the armature of relay R is acted upon as a result of the flow of currents through windings W and W causing it to strike contact S, current will flow from battery 13" through resistance Z armature of relay R this current then dividing so that part of it flows through the upper half of winding W and resistance Z and so that the rest of the current flows through the lower half of winding W and condenser G. Thatcurrent' which flows through the upper half of winding W and resistance Z will be in such a direction as to set up a magnetic field tending to cause the armature to leave contact: S. The initial current flowing through the lowerhalf of winding V7 and condenser 0, however, will be considerably larger than the former current and will be in such a direction as to establish a magnetic field about the lower half of winding Vv 'opposing that field set up by the current through the upper half of the winding W and aiding the effect producedby windings N and W The relay armature will therefore have less tendency to chatter than would be the case if this so-called vibrating circuit were not connected.

It is not long before the condenser C becomes fully charged, whereupon the current flow through the lower half of winding W becomes reduced to zero; while the current through the upper half of winding W and resistance Z remains steady and tends to cause the armature to leave contact S. This armature cannot leave contact S, however, as long as the stronger magnetic effect of the currents through windings W and W is maintained, whereby the armature is held against contact S. When the magnetic field caused by the flow of currents through windings W and W is reversed, however, due to the action of relay R the armature of relay R will leave contact S more easily than would be the case if the current'through the upper half of'the winding W and resistance Z were not present. By virture of'the presence of the vibrating circuit, and of the action of its winding W relay R is made quite sensitive in its action.

When the armature of relay R opens contact S in its travel to contact M, neither of the batteries B nor- 13" will be connected current will flow from battery B 2 through resistance Z the armature of relaylt and contact M and this current will then divide so that part of it flows through the upper half of winding W and resistance Z the remainder flowing through the lower half of winding W and condenser (l. The current through the upper half of W, and resistance Z will continue tofiow as long as the armatureot relav R is oncontact M. But the current through the lower half of winding xvV and through condenser C will flow at a diminishing rateuntil condenser C becomes charged to thepotential of battery B condenser C being now charged to a polarity opposite to that which it had whenthe armature closed contacts. Thischargingcurrent through condenser G will produce a magi'ietic field aboutthe lower half of winding W which will aid that established by i windings W and W in holding the armature of relay R against contact M, thereby preb venting chatter.

The current flowing through a the upper half of winding W and resistance Z will set i up amagneticfield opposing that set up around windings W and l/V and that set up by the lower half of winding W Immediately after the armature closes contact M,

however, the current through the lower half of winding W5 and condenser C willbe much i I larger thanthat through the upperhalfof winding W and resistance Z so that at first the eliective magnetic field due to winding: W, will aid the effective magnetic field established by the currents through windings W and W thereby holding the armature against contactM.

After the current charging condenser C has decreased to a value less than that flowing through the upperhalf of winding W and through resistance Z the efiective magnetic field about winding W} will be reversed and .will oppose that field established by Windings N and 7 Thenthe field of winding 7W will aid that producedby windings W and W upon a reversal of the magnetic field cue to the action of relay R When the armature of relay R again closes its contact, r the armature of relay R will promptly close.

its contact S in the manner already described hereinabove.

it is to be noted when the armature of relay R begins to leave contact M, current will flow through both portions of winding W due to the charged condition of condenser C, the magnetic fieldestablished by winding l/V tending to sharply kick the armature of relay R against the spacing contact S. WVhen the armature oi relay R finally reaches contact S, the cycle of events already describedhereinabove will be renewed.

- The vibrating circuit of Fig. 1 operates upon substantially the same principles as those described in connection with the circuit of Fig. 2; yet, the one shown in Fig. 1

is even more eiiective due to the presence of the coupled windings W4 and W These windings may be employed to boost the effective voltages sothat the movement of the a armature between its contacts maybe even more rapid.

It willbe understood that the relay R of this invention is one having an armature which remains fixed against its contact for its spacing condition and vibrates at a high periodicity forits marking condition. a

t will be also apparent that the combination of the two relays R and R and the associated equipment, may take the place of a present vacuum tube amplifier, detectors and direct currentrelays now employed in telegraph receiving systems for receiving pulsationsoli alternating current corresponding to telegraph signals. Relay. R may be considered to perform the function of an amplifier and a detector, and relay R may be considered to actin somewhat the same manner as the present direct current relay. a The principles of this invention may be employed rent relay, a direct current relay, means for causing the armature of the direct current relay to close one of its contacts when energy is being supplied to the alternating current relay, means for causingthe armature of the direct current relay to close the other of its contacts when no energy is being supplied to the alternating current relay, and means for maintaining the potential dili'erence between the armature of the alternating current relay audits contact below a predetermined value. 2. The combination of an alternating current relay, means whereby pulses of high frequency current corresponding to the telegraphflsignals may beimpressed upon the winding olthe alternating currentrelay, a directq current relay having an armature which may move between two contacts,means whereby the armature of the direct current a relay may close one of its contacts when a pulse of high. frequency current is being 11npressed upon the windingofthe alternating current relay, means whereby the armature of the direct current relay may close the other of its contacts when no pulse of high froquency current is being impressed upon the winding of the alternatingcurrent relay,

and means for controlling the potential difference impressedbetween the armature of the alternating current relay and its contact.

3. The combination of an alternating currentrelay, a direct current relay, a line operated by the armature of the direct current relay, means for impressing pulses of alternating current upon the winding of the alternating current relay in accordance with marking and spacing signals characteristic of telegraphy, means for moving the armature of the direct current relay to one of its contacts and to remain on that contact when a pulse of alternating current is impressed on the winding of the alternating current relay,'means for movingthe armature of the direct current relay to the other of its contacts when no alternating current pulse is impressed on the winding of the alternating current relay, and, means for maintaining the potential difference between the armature of the alternating current relay and its contact below a predetermined value.

4. Thecombination of an alternating current relay, a direct current relay, means for impressing telegraph signals upon the winding of the alternating current relay, means for operating the armature of the direct current relay in accordance with the marking and spacing signals characteristic of said impressed telegraph signals, and means for maintaining the potential difference between the armature of the alternating current relay and its contact below a predetermined value.

5. The combination of an. alternating current relay, a direct current relay having two 7 operating windings, one of the operating windings of the direct current relay being in series with the armature ofthe alternating current relay and its contact, a source of low voltage direct current connected in parallel to the other operating winding of the direct current relay and in parallel to the first operating winding of the direct current relay and the armature of the alternating current relay and its contact, a line controlled by the armature of the direct current relay, and means including a pair of sources of high voltage direct current for impressing currents of opposite polarities. upon said line through the armature of the direct current relay.

6.'The combination'of an alternating current relay having coupled windings, a direct current relay, an input circuit coupled to the winding of the alternating current relay, signaling currents flowing through said input circuit, an output circuit controlled by the tan mature of the direct current relay, and means interconnecting the armature of the alternat ing current relay andthe two coupled windings of the direct current relay to cause the output circuit to become energized in accord ance with those signaling currents flowing in said input circuit I 7. The combination of a tuned, sensitive alternating current relay the winding of which is connected to a circuit over which may fiow pulses of alternating current, the armature of the alternating current relay vibrating with each pulse and at a periodicity corresponding to the frequency of the alternating current and being at rest between pulses, a polar direct current relay having two coupled, operating windings, circuit arrangements interconnecting the armature of the alternating current relay and its contact and one of the operating windings of the direct current relay whereby pulses of direct current may become impressed upon both of the operating windings of the direct current relay corresponding to those alternating current pulses flowing in the winding of the alternating current relay, and alocal circuit controlled by the armature of the direct current relay and receiving direct current pulses corresponding to the pulses of alternating current flowing in the circuit connected to the winding of the alternating current relay.

8. The combination of a polar alternating current relay the winding of which issupplied with alternatin current pulses corresponding to signals, means for maintaining the potential difference between the armature of the polar alternating current relay and its contact below a predetermined value, a line circuit suitable for the transmission of direct currents representative of the alternating current pulses supplied to the winding of the polar alternating current relay, a pair of op positely poled batteries, and means interconnecting said line circuit and the polar alternating current relay to cause said line circuit to be supplied with direct current from one of said batteries when no alternating cur rent pulse'is flowingthrough the winding of the alternating current relay and to cause said line circuit to be supplied with direct current of opposite polarity from the other of said batteries when an alternating current pulse is flowing through the winding of the alternating current relay. 7

In testimony whereof, I have signed my name to this specification this 3rd day of May, 1928. v V y FRED J. SINGER. 

